Gin no Oni

From Amazon: A tale of forbidden love – a demon and a girl “You are gonna have my baby, a demon baby!” – The demon pursues 17-year-old girl Fubuki… As a child Natsuno Fubuki met a silver demon. He told her : "When you grow older, I'll definitely come and eat your heart" Fubuki, who grew up, at the age of 17 while frightened of the memory of that demon, had a crush on her homeroom teacher, Shimakage Tone, and told Shimakage-sensei about her feelings and the horrible memory of the demon. But her teacher said "That is me" and turned into the demon?! A forbidden love fantasy that depicts the mysterious bond between a girl and a demon that has been lonely for a thousand years!